As one relevant apparatus of the air-intake apparatus as arranged above, Patent Document 1 discloses a construction comprising an intake manifold including a branched tube portion for introducing air in the surge tank to the engine, a bypass air-intake passage for directing the air in the surge tank to a terminal portion of the intake manifold, and a rotary valve for allowing or breaking communication with the bypass passage. In the apparatus of Patent Document 1, the bypass passage is closed with the rotary valve when the engine is rotated at low seed, thereby to achieve an inertia supercharging effect by supplying air through the intake manifold with a long air-intake passage. On the other hand, when the engine is rotated at high speed, the rotary valve allows the communication with the bypass passage, thereby to supply a large amount of air can be supplied with a short air-intake passage.
With the air-intake apparatus of Patent Document 1, the rotary valve includes a casing and a rotor. Further, since the inertial supercharging effect is marred when the air flows from the bypass passage with the air being supplied with a long air-intake passage, a gasket is provided between the rotor and the casing. As a specific construction for providing the gasket, the rotor includes an annular groove extending along an outer circumference of the rotor in a circumferential direction and a linear groove extending along a rotational axis. The gasket includes an arc sealing portion fitted into the annular groove and a linear sealing portion fitted into the linear groove, both of which are integrally formed with each other. With such a construction, the arc sealing portion is fitted into the arc groove while the linear sealing portion is fitted into the linear groove, thereby to allow the gasket to be supported to the outer surface of the rotor.
On the other hand, Patent Document 2 discloses a construction comprising a rotatable switching roller (corresponding to the rotary valve of the present invention) for switching the length of an air-intake tube in the similar manner to the apparatus of Patent Document 1, and a sealing element provided in the switching roller for enhancing the sealing efficiency. The sealing element includes a pair of linear sealing pieces extending parallel to each other and ring elements provided in opposite ends of the sealing pieces, which are integrally formed with each other. The sealing element is fitted into an outer surface of the switching roller to be engageably supported.